Planetary gearbox having a ring gear accommodated in a housing part

ABSTRACT

A planetary gearbox includes a ring gear accommodated in a housing part, the ring gear particularly has on its radially outer surface, in particular its radially outer side, an annular groove, the annular groove, in particular a circumferential annular groove in the circumferential direction, and a spring element is accommodated in the annular groove, which projects at least partially into an annular groove introduced into the housing part.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/349,356, which is the national stage of PCT/EP2017/025318,having an international filing date of Oct. 25, 2017, and claimspriority to Application No. 10 2016 013 395.3, filed in the FederalRepublic of Germany on Nov. 11, 2016, each of which is expresslyincorporated herein in its entirety by reference thereto.

FIELD OF THE INVENTION

The present invention relates to a planetary gearbox having a ring gearaccommodated in a housing part.

BACKGROUND INFORMATION

It is generally conventional that planetary gearboxes include a ringgear.

German Published Patent Application No. 10 2015 202 161 describes aconnection system.

European Published Patent Application No. 0 239 556 describes a couplingbetween two elements.

U.K. Published Patent Application No. 770 659 describes an improvementrelating to annular stops.

U.S. Pat. No. 2,831,716 describes a releasable coupling.

German Published Utility Model Application No. 19 22 273 describes asnap ring.

German Published Patent Application No. 837 341 describes a device forsecuring a component on a shaft against an axial displacement.

U.S. Patent Application Publication No. 2013/0345009 describes a drivedevice for a vehicle.

SUMMARY

Example embodiments of the present invention provide for simplifying themanufacture of a planetary gearbox.

According to an example embodiment of the present invention, a planetarygearbox includes a ring gear, which is accommodated in a housing part,and the ring gear has an annular groove, in particular an annular grooveextending in a circumferential direction, on its radially outer surface,in particular the radial outer side, a spring element being accommodatedin the annular groove, which at least partially projects into an annulargroove introduced into the housing part.

This is considered advantageous insofar as the spring element is pressedinto the annular groove when the ring gear is inserted into thereceiving opening of the housing part and radially expands once itreaches the annular groove of the housing part. Toward this end, thespring element has a conical configuration, the tip of the cone pointingin the insertion direction. Using the relaxed, i.e. radially expanded,spring element, a keyed connection is obtained since the spring elementprojects at least partially into both annular grooves.

According to example embodiments, the spring element is arranged in anannular shape, and/or the spring element is arranged as an apertureddisk. This has the advantage of allowing for a simple production, inparticular as a punched and bent component.

According to example embodiments, the smallest radial clearance value ofthe apertured disk at a respective axial position increasesmonotonically in the axial direction, and the greatest radial clearancevalue of the apertured disk at a respective axial position increasesmonotonically in the axial direction. This is considered advantageousinsofar as the spring element is preloaded counter to the axialdirection, without stopping, when the spring element is inserted intothe housing part together with the ring gear.

According to example embodiments, the smallest radial clearance value ofthe apertured disk at a respective axial position increasesmonotonically counter to the axial direction, and the greatest radialclearance value of the apertured disk at a respective axial positionincreases monotonically counter to the axial direction. This has theadvantage of making it easy to provide a constant wall thickness.

According to example embodiments, the spring element has a constant wallthickness. This is considered advantageous insofar as it allows for asimple production using steel plate.

According to example embodiments, the spring element is a punched andbent component, in particular a punched and bent component made of steelsheet. This has the advantage of simplifying the production.

According to example embodiments, the spring element has a radiallyuninterrupted slot at a circumferential position and/or the springelement has a respective radially uninterrupted slot at at least twocircumferential positions. This offers the advantage that a more elasticconfiguration is achievable.

According to example embodiments, the spring element is axiallypreloaded, so that the ring gear and the housing part are axially pushedapart, in particular such that bearings, which support a planet gearcarrier and are accommodated in the housing part, are pressed against astep formed on the housing part and are preloaded. This has theadvantage that the housing part exerts pressure on the ring gear,especially counter to the axial direction, with the aid of the springelement, and is thereby pressed onto one of the bearings, which exertspressure on a second bearing, which is pressed against the step andpreloaded as a result.

According to example embodiments, the annular groove introduced into thehousing part has a chamfer at its first axial end region, in particularfor the purpose of introducing the spring element into the annulargroove developed on the housing part. This has the advantage that thechamfer allows the spring element to be easily inserted into the annulargroove of the housing part. In other words, the chamfer guides thespring element into the annular groove when the spring element relaxes.

According to example embodiments, the annular groove introduced into thehousing part has a groove wall which includes a planar region, thenormal direction of the planar region with respect to the axialdirection having a non-zero angle, in particular an angle between 20°and 70°. This offers the advantage of allowing for a defined guidancewhen the spring element is relaxed.

According to example embodiments, the spring element has a toothed orknurled configuration at its radially inner circumference and/or outercircumference, the teeth of the tooth system in particular being spacedapart from one another at regular intervals in the circumferentialdirection. This is considered advantageous insofar as it allows forbetter securing of the spring element against a rotation in thecircumferential direction.

According to example embodiments, the spring element is braced at thebottom of the annular groove introduced into the ring gear on the onehand, and at the chamfer of the annular groove introduced into thehousing part on the other hand. This has the advantage of allowing forstable bracing in the edge region of the annular groove.

According to example embodiments, the planet gear carrier accommodatesplanet pins, on which a planet gear is situated which is rotatablymounted with the aid of the respective bearing, the tooth system of therespective planet gear meshing with the inner tooth system of the ringgear and meshing with the tooth system of a sun gear that is rotatablysupported relative to the housing part on the other hand, the sun gearin particular being situated coaxially with respect to the planet gearcarrier. This offers the advantage that a planetary gearbox is able tobe produced in a simple manner.

Further features and aspects of example embodiments of the presentinvention are described in greater detail below with reference to theappended Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a cross-section through a planetary gearbox according to anexample embodiment of the present invention, ring gear 3 being connectedto a housing part 1 of the planetary gearbox by a keyed connection withthe aid of a spring element 2.

FIG. 2 shows ring gear 3 prior to the keyed connection with the aid ofspring element 2.

FIG. 3 illustrates the start of the snap-in process of spring element 2into an annular groove of housing part 1, spring element 2 sliding alonga chamfer of the annular groove.

In FIG. 4, spring element 2 is shown snapped into the annular groove ofthe housing part.

FIG. 5 shows an enlarged view of FIG. 1.

In FIG. 6, spring element 2 is shown in a side view, in a plan view andin an oblique view.

In FIG. 7, another spring element 2 is shown in a side view, a plan viewand in an oblique view.

FIG. 8 shows a further spring element 2 in a plan view.

DETAILED DESCRIPTION

As illustrated in FIG. 1, the planetary gearbox includes a ring gear 3having an internal tooth system, which is situated in a housing part 1of the planetary gearbox by a keyed connection.

The tooth systems of planet gears 6 mesh with the internal tooth systemof ring gear 3.

Via bearings 5, in particular needle bearings, planet gears 6 arerotatably mounted on planet gear axles, which are pressed into a planetgear carrier 9.

Planet gear carrier 9 is rotatably mounted in housing part 1 with theaid of two bearings 8.

The tooth systems of planet gears 6 also mesh with the tooth system of asun gear 7, which is also rotatably mounted, in particular relative tohousing part 1.

The axis of rotation of planet gear carrier 9 and the axis of rotationof sun gear 7 are aligned coaxially to each other.

A circumferential annular groove is introduced at the outercircumference of ring gear 3; in the same manner, an annular groove isintroduced into the inner side of housing part 1.

As illustrated in FIGS. 2 through 4, spring element 2 is placed into theannular groove of ring gear 3 during the assembly and is elasticallydeformed when slipped into the bore hole provided to accommodate ringgear 3 in housing part 1, such that it is fully situated in the annulargroove of the ring gear.

At its one axial edge region, the annular groove introduced into housingpart 1 has a chamfer, i.e. a circumferential bevel in thecircumferential direction.

As soon as this chamfer reaches the axial region of the annular grooveof housing part 1 when ring gear 3 is inserted into housing part 1,spring element 2 begins to relax and gradually slides along the chamferinto the annular groove of housing part 1 via its first axial endregion.

In the relaxed state, the radial clearance region covered by springelement 2 in relation to the axis of rotation of planet gear carrier 9overlaps both with the radial clearance region covered by ring gear 3and the radial clearance region covered by housing part 1, in particularin the axial region covered by spring element 2.

Spring element 2 may be axially preloaded so that ring gear 3 andhousing part 1 are axially pushed apart. Spring element 2 thereforegenerates a spring force that exerts pressure on the ring gear counterto the axial direction and on the housing part in an axial direction.

As illustrated in FIG. 6, spring element 2 is arranged as an apertureddisk, i.e. in the form of a ring.

The ring axis of the apertured disk is arranged coaxially to the axis ofrotation of planet gear carrier 9.

The inner diameter of the apertured disk corresponds to the smallestdiameter of the annular groove introduced into ring gear 3. As a result,the inner edge of the apertured disk rests against the bottom of theannular groove introduced into ring gear 3.

After the outer edge of the apertured disk has been pressed along thechamfer into the annular groove introduced into the housing part duringthe production while the spring element, i.e. the aperture disk, isrelaxed, the outer edge of the aperture disk rests against the groovebottom of the annular groove introduced into housing part 1.

Starting from the inner edge of the apertured disk towards the outeredge of the apertured disk, the radial region covered by the apertureddisk increases monotonically as a function of the associated axialregion covered by the apertured disk.

The apertured disk may have a constant wall thickness.

The radial clearance region covered by the apertured disk at arespective axial position monotonically shifts to greater radialclearances in the axial direction as a function of an increasing axialposition. In other words, the smallest radial clearance value of theapertured disk at a respective axial position monotonically increases inthe axial direction and the greatest radial clearance value of theapertured disk at a respective axial position monotonically increases inthe axial direction.

The radially outer circumference of the apertured disk may correspond toa frustoconical surface, and the radially inner circumference of theapertured disk corresponds to a frustoconical surface as well.

This makes spring element 2, which is arranged as a punched and bentcomponent from sheet metal, in particular steel sheet, easilydeformable.

As illustrated in FIG. 6, spring element 2 has a radially uninterruptedslot at a circumferential position for an easier deformation. Thedeformability may thus take place in a defined manner.

As illustrated in FIG. 7, instead of the previously described springelement 2, it is also possible to use a spring element 2 that has atoothed or notched configuration at its radially outer edge, which againresembles an apertured disk in all other respects. The elevated areas ofthis tooth system are set apart from one another at regular intervals inthe circumferential direction and have a rectangular shape in thecircumferential direction.

As illustrated in FIG. 8, spring element 2 may also have a slot, inparticular a radially uninterrupted slot, at more than onecircumferential position. Even better elastic deformability is therebyachievable. This additional slot may be used in the example embodimentsdescribed herein.

Spring element 2 may be circular at its axially frontal region and mayalso be circular at its axially rear region.

LIST OF REFERENCE NUMERALS

-   -   1 housing part    -   2 spring element    -   3 ring gear, in particular ring gear having an internal tooth        system    -   4 planet gear carrier    -   5 bearing, in particular needle bearing    -   6 planet gear    -   7 sun gear    -   8 bearing    -   9 planet gear carrier

What is claimed is:
 1. A planetary gearbox, comprising: a housingincluding a first annular groove on a radially inner surface; a ringgear accommodated in the housing and including a second annular groovein a radially outer surface; and a spring element at least partiallyprojecting into the first annular groove and the second annular groove;wherein the first annular groove includes a planar region, a normaldirection of the planar region having a non-zero angle in relation to anaxial direction of the ring gear, the spring element engaging the planarregion.
 2. The planetary gearbox according to claim 1, wherein thespring element extends substantially perpendicular to the planar region.3. The planetary gearbox according to claim 1, wherein the first annulargroove or the second annular groove is arranged as a circumferentialannular groove in a circumferential direction.
 4. The planetary gearboxaccording to claim 1, wherein the spring device is arranged as a ringand/or an apertured disk.
 5. The planetary gearbox according to claim 1,wherein the spring device is circular in an axially frontal region andan axially rear region.
 6. The planetary gearbox according to claim 1,wherein the spring device is arranged as an apertured disk, a smallestradial clearance value of the apertured disk at a respective axialposition increases monotonically in an axial direction, and a greatestradial clearance value of the apertured disk at a respective axialposition monotonically increases in the axial direction.
 7. Theplanetary gearbox according to claim 1, wherein the spring device isarranged as an apertured disk, a smallest radial clearance value of theapertured disk at a respective axial position monotonically increasescounter to an axial direction, and a greatest radial clearance value ofthe apertured disk at a respective axial position monotonicallyincreases counter to the axial direction.
 8. The planetary gearboxaccording to claim 1, wherein the spring device has a constant wallthickness.
 9. The planetary gearbox according to claim 1, wherein thespring device is arranged as a punched and bent component.
 10. Theplanetary gearbox according to claim 9, wherein the spring device isarranged as a punched and bent component produced from steel sheet. 11.The planetary gearbox according to claim 1, wherein the spring deviceincludes a radially uninterrupted slot at a circumferential position.12. The planetary gearbox according to claim 1, wherein the springdevice includes a radially uninterrupted slot at a plurality ofcircumferential positions.
 13. The planetary gearbox according to claim1, wherein the spring device is axially preloaded so that the ring gearand the housing are axially pushed apart.
 14. The planetary gearboxaccording to claim 1, wherein the spring device is axially preload sothat the ring gear and the housing are axially pushed apart and suchthat bearings, supporting a planet gear carrier and accommodated in thehousing, are pressed against a step provided on the housing andpreloaded.
 15. The planetary gearbox according to claim 1, wherein theangle is between 20 degrees and 70 degrees.
 16. The planetary gearboxaccording to claim 1, wherein the spring device is toothed and/orknurled at a radially inner circumference and/or outer circumference.17. The planetary gearbox according to claim 16, wherein the teeth ofthe spring device are set apart from one another at regular intervals ina circumferential direction.
 18. The planetary gearbox according toclaim 1, wherein the spring device is braced at a bottom of a first oneof the first annular groove and the second annular groove and on theplanar region of a second one of the first annular groove and the secondannular groove.
 19. The planetary gearbox according to claim 1, whereinplanet lugs are provided in a planet gear carrier, a planetary gearbeing provided on each planet lug and supported by a respective bearing,a tooth system of the planetary gear meshing with an internal toothsystem of the ring gear and meshing with a tooth system of a sun gearwhich is rotatably supported relative to the housing.
 20. The planetarygearbox according to claim 19, wherein the sun gear is arrangedcoaxially to the planet gear carrier.
 21. The planetary gearboxaccording to claim 1, wherein the first annular groove and the secondannular groove are arranged as circumferential annular grooves in acircumferential direction.